Second step in setting up your cart - templates

[kuroi]

Can someone please help me understand what the advantage and disadvantage of both methods is, and why the general rule re: editing existing files wouldn't seem to apply here?

In so far as there is a general rule about editing existing files in Zen Cart, it is "Don't".

For most changes you would create an over-ride file and place it in a template folder. As you get deeper into the code, slightly different methods are needed, especially if your changes may be applicable to more than one template. SermonZone is explaining one of them.

The reason for this is that if you change the original files, then there is a good chance that your changes will get get over-written and lost when you upgrade to later versions of Zen Cart.